As it was found out, there are some problems in translating the 1992
Vasil'ev's article into English using http://babelfish.altavista.com/.
So I have done it with the translator in several steps, making some minor
corrections. I hope that it is possible to understand its main aspects,
at least. :)
Russian part of its bibliography is in Russian, so there can be some
problems
while reading it (due to different codes).

[Abstract]
In the article the basic data about physics of Tunguska explosion and about
the results of the searches
for the substance of the tunguska meteorite are cited. Ideas about the
complex nature of this phenomenon and about the high degree of its
complexity are based. It is indicated the difficulty of the interpretation
of Tunguska phenomenon within the framework of the existing scientific
paradigm, including the most common at present hypothesis about comet nature
of the tunguska meteorite. It is indicated a number of the paradoxical
circumstances, which relate to the trajectory of Tunguska cosmic body, to
the geophysical consequences of Tunguska catastrophe and to the biological
consequences in the region of explosion generated by it. It is indicated the
need of developing the alternative versions of the interpretation of
Tunguska phenomenon.
[end of the abstract]

A question about nature of the tunguska meteorite
remains unresolved up to now, in spite of the long-standing efforts
of the researchers of problem. Hypotheses proposed for explaining this
phenomenon are divided into two groups: 1) proceeding from the idea about
the belonging of the tunguska meteorite (TM) with one of the categories of
the small bodies of the solar system [ 1-3, 23, 31-35, 46, 47 ] - to
asteroids or to comets; 2) assuming its uncommon, including technogenic
nature [ 2, 15, 16, 43-45 ]. The entering the first group hypotheses about
the tunguska meteorite as about the small asteroid [ 24, 25 ] at present are
practically disavowed and are in essence of historical interest. Preserved
its value and undergoes further development comet hypothesis [ 18, 31-35 ].
In the number of alternative it the versions, entering the second group of
hypotheses, should be isolated the version, about the tunguska meteorite as
about the plasmoid [ 13 ] and about technogenic extraterrestrial nature TM
15, 16 ].

Taking into account the circumstance that the majority of
researchers in a question about nature of the tunguska meteorite adhere to
comet hypothesis, it is expedient to discuss a number of paradoxical,
including of little-known, circumstances of the Tunguska catastrophe, which
with difficulty are plotted in the framework of this concept. Ignoring these
moments/aspects can push further development of problem to the false way and
hinder its final solution.

It would be erroneously consider that the specific feature, which
releases Tunguska phenomenon from a number of other
incidences/falls of gigantic meteorites, is exclusively its scale. The
TNT equivalent of Tunguska explosion (10-40 Mt.) and its energy (10^23-10^24
ergs) undoubtedly is very great; however, they are not the upper limit of
the energy parameters, which characterize similar phenomena. Thus, the
energy, which was isolated with the formation of Popigayskoy astrobleme,
several orders exceeded energy of the tunguska meteorite. Its many-sidedness
is the main specific feature of Tunguska phenomenon, and this circumstance
must be considered during the construction of any concept, which claims to
the explanation of this phenomenon as a whole. It is necessary to have in
the form that the explosion of cosmic body on the Podkamennaya Tunguska
[river] 30.06.1908 year was the brightest, culmination, but far from only
episode in the compound circuit of the anomalous natural phenomena, which
unrolled in the summer of 1908.

Discussing the paradoxical circumstances of Tunguska
catastrophe, it is necessary, first of all, to stop at some special features
of its motion in the atmosphere of the Earth.

It is known that explosion TM preceded the flight/span above central
Siberia of gigantic day bolide, which
was being accompanied by the exceptionally/exclusively powerful sonic
and luminous effects [ 10 ]. The analysis of the catalog of the
statements of the eyewitnesses of the catastrophes [ 11 ], whose total
number reaches several hundred, is revealed the not elucidated up to now
circumstance, consisting in the fact that the thunderous sounds were
observed not only during and after the flight of bolide, but also before
it. This information is contained in the number of the statements of
eyewitnesses, which were being located at the moment of event in the
populated areas on Angara [river], including in the completely detailed
description of event by the political deportee, which lived in the village
of Kezhma - by man with sufficiently high (judging by everything)
educational level. To explain [this] by their subjective errors is hardly
actual, since similar assertions are repeated repeatedly and independently
of each
other. Since/as observers were frequently located from the zone of the
projection of trajectory at a distance, measured as the minimum by tens of
kilometers, then it is obvious that the reason for sounds in this case the
ballistic
wave deliberately could not be, since it was capable of lagging behind the
bolide, but of not passing it. The singularly real explanation of this
circumstance consists of the assumption of its relation with the
powerful electromagnetic phenomena; however, the up to now
considered/examined question is not studied from this point of view.

The second, sufficiently strange, circumstance is connected/bonded
with the direction of the motion of body. The analysis of the statements of
witnesses, assembled on the hot tracks of event [ 11 ] and into the 20th -
30-s years [ 25, 28 ], led the first researchers of problem (L.A. Kulik,
I.S. Astapovich, E.L. Krinov) to the unanimous conclusion about the
fact that the bolide flew in the direction from the south to the north.
However, the analysis of the vector structure of forst-fall, caused by
the shock wave of the tunguska meteorite, gives azimuth 114degrees [ 29,
30 ], and the field of burn damages - even 95degrees [ 6-8 ], i. e.
testifies
about the motion of meteorite almost from the east to the West. It is
necessary to add that this direction is confirmed by the analysis of the
statements of
eyewitnesses, which lived at the moment of event in the upper reaches of
Nizhnyaya Tunguska [river] (region of Preobrazhenki, Yerbogachen and Nep).

The nonconformity occurring is obvious. Attempts at its explanation
were undertaken repeatedly and from different positions. Is expressed, in
particular, assumption [ 13 ] about the fact that 30.06.1908 g. above
central Siberia occurred the flight not of one, but several bolides.
This treatment, however, is extremely stretched along that reason, that
among of many hundreds documented statements of eyewitnesses there is not
one, in which would be mentioned two bolides, observed during one day,
although the overlap of visibility ranges in the case in question more than
is probable. Great discussion caused F. Yu. Ziegel's version about the
maneuver TM in the Earth's atmosphere. It, however, can be discussed in
earnest, only if we assume that nature of Tunguska cosmic body is
technogenic.

The culmination of the flight of the tunguska meteorite was the
explosion-like energy discharge, whose TNT equivalent was from 10 to
40 megatons with the larger probability of the upper level of
estimations/evaluations [ 20-22, 27, 41 ]. Detailed fracture characteristic,
caused by shock wave, and also seismic, baric and other effects of Tunguska
explosion is contained in a number of sources [ 1, 2, 27, 46, 47 ]. One of
the most important primes in the " portrait " of vectorial field of the
forest-fall, formed by the shock wave, is the presence of the axisymmetrical
deviations from a strict radiality, which occur in the zone of the
projection of trajectory [ 29, 30 ] and being the track of ballistic wave.
Further detailed analysis of vector structure led, however, to the
conclusion that the axisymmetrical deviations occur not only before the
epicentre, but also after it, on the continuation of trajectory. Since the
action of ballistic wave is the only explanation of these deviations from
the radiality proposed, hence follows the conclusion that the tunguska
meteorite (or, at least, its part) did not finish its existence at the
moment of explosion, but continued its motion along the trajectory with
supersonic speed. If it takes into account that the nucleus/kernel of the
comet (as tunguska meteorite presumably was it) consisted of the chunks
of the freezing gases with a density of 1 g/cm^3, it is unclear, how the
object, which has similar characteristics, could at least be preserved
partially, after undergoing the super-power thermal and mechanical loads,
described above.

Key component in the study of nature of the tunguska meteorite is a
question about that, such as was its material (element and isotopic)
composition. Beginning from the expeditions L.A. Kulik, the searches
for the substance of the tunguska meteorite were occupied several
generations of researchers. The sums of these long-standing efforts
are reflected in the numerous surveys/coverage and the original publications
[ 23-25 ], nevertheless, today it is possible with the full responsibility
to assert that the space substance ( which it would be possible to
guaranteedly identify with the substance of the tunguska meteorite) is not
found yet. To explain this negative result by insufficient sensitivity, the
adapted procedures is impossible for two reasons.

First, the same methods successfully are used with the fulfillment of
the works of ecological profile/airfoil for the development/detection of the
tracks of precipitation of industrial aerosols in the quantities,
commensurate with those forecasted in this situation [ 6-8, 36-40 ].

In the second place, in peats and soils of the impact area in the
tunguska meteorite by the same methods it is discovered as the minimum of
five forms of the fine dispersed space substance, which is the tracks of
background
global precipitation of the cosmic dust [ 6-8 ]. It is completely
understandable that if the sensitivity of the utilized procedures is
sufficient for the development/detection of background precipitation, there
are no foundations for considering them insufficient for the
development/detection of the refractory fine dispersed substance of the
tunguska meteorite in the case of its presence.

Explanation ( of the [negative] result indicated) by the absence in the
comet nuclei/kernels of significant quantities of refractory material is
vulnerable: sounding/probing Halley's comet within the framework of
projects " Vega " and " Giotto ", although it did not make possible of a
strict quantitative estimation of the fraction/portion of refractory
component in the composition of comet nucleus/kernel, makes it possible to
nevertheless consider that its contribution to the overall nuclear mass
cannot be negligible.

In connection with this, an opinion is expressed about the fact that the
tunguska meteorite had, possibly, the composition uncommon for the small
bodies of the solar system. Although there are no direct proofs to this,
there are indirect circumstances, its confirming. They include the detection
by Italian researchers Galli, Cecchini, etc. [ 42 ] in resin of 1908 of the
trees/wood, which survived Tunguska explosion near its epicentre, aerosol
particles, which contain bismuth, the connection of tungsten with cobalt
also of lead with bromine. Does not contradict the aforesaid a " peak "
increase in the concentration of rare-earth elements, especially ytterbium,
in the samples of the soils, selected near the calculated center of probable
precipitation of the substance of the tunguska meteorite [ 6-8 ]. Without
attaching much importance to these findings, it would be incorrectly
underestimate them, since the discussion deals with the clearly nontrivial
event.

Many questions cause the biological consequences of Tunguska explosion, in
particular the discovered by the methods of mathematical population genetics
effect of an increase of the genotypic changeability in pine tree in the
region of catastrophe [ 14 ]. this effect is statistically highly reliable,
it gravitates towards to epicentre and projection of trajectory and it is
not reduced to the action of fire, of forest-fall and other known changes
in the ecological situation. Its reason remains unexplained. The study of
the radioactivity of soils and plants in the region of catastrophe
oscillations/variations in the limits of natural background revealed,
although its values from the epicentre somewhat hereabout exceed the same to
periferin of region [ 9 ]. The study of changes in the thermoluminescence
properties of the rocks [ 5 ] and soils [ 4 ], which are the indicator of
radiation exposure on the
objects in the past, they revealed the complex picture, which does not
contradict idea about the possible presence in the spectrum of the physical
factors of the Tunguska explosion of the ionizing radiation. The absence of
the increased radioactivity in comparison with the natural background in the
region of epicentre cannot serve as base for its negation in the past,
since, in the first place, Tunguska explosion occurred at the height of 5-7
km, which minimizes its hypothetical local radiation consequences, in the
second place, since then to the moment of the first (completely
rough) measurements have passed more than 50 years - period, is more than
sufficient for normalizing/standardizing the summary radioactivity even in
the places of nuclear test.

Besides local Anomal Phenomena of 30.06.1908 g. in central Siberia the
summer of 1908 was marked by the complex of the optical anomalies of night
and twilight sky, which began for several days before the event, which
reached/achieved
culmination on the night from 30 June on 1 July, exponentially decreasing on
the intensity to the subsequent 2-3 days and finally died out toward the end
of July of month. The basic components of this anomalous optical complex
they were bright ("volcanic") twilights, extraordinary according to the
power propagation of the fields of noctilucent clouds at the height of 80 km
and, apparently, the intensification of the emission of night sky. Detailed
description and catalog of these phenomena are given into [ 17, 26 ],
they are explained usually by introduction into the upper air of the Earth
simultaneously with the fall of the meteorite of finely dispersed material
the comet origin- more concrete/more specific, comet tail. However, the
latter was deflected by the pressure of solar rays/beams to the side,
opposite to the sun, which at 7 A.m. of local time was found almost
accurately in the east. Such the explanation, usually given in the
description of the mechanism of " bright nights " 1908 more thorough
analysis reveals, however, a number of the serious difficulties, which can
be brought to the following basic moments.

First, the considerations, given in [ 17 ], show that in the situation
in question the tail of hypothetical comet had to lie not on Western Europe
or
European territory of Russia and all the more not in the North Caucasus,
but, " after throwing " across the north pole, in Canada, which in actuality
was not.

In the second place, Academician V.G. Fesenkov [ 31-34 ], to whom
belongs the most complete substantiation of comet hypothesis, showed that
the
particles of the cometary tail in view of their small sizes/dimensions must
be detained at the height of 200 km and it is higher only gradually to
parachute then from there for the duration of long time. Meanwhile
noctilucent clouds are located on the height of 80-82 km, and dawn-like
phenomena are formed at the height of 50-60 km. Even below
occur processes, which ensure changes from the side of atmospheric
polarization, to say nothing of numerous during those days solar halo. All
this led V.G. Fesenkov to the need for excluding from the number of
atmospheric optical effects, connected/bonded with the tunguska meteorite,
practically all forms of anomaly, except one - its own emission of night
sky, whose presence, by the way speaking, is least proved, since the direct
measurements of emission yet were not accomplished at that time.

In the third, basic structural components of comets are a head, a tail
and a coma. The diameter of gas-dust coma in the comet, whose size/dimension
corresponds to the assumed Tunguska, is measured by hundreds of kilometers,
whereas dustiness in it is considerably higher than in the tail. It is
logical therefore to expect that upon entry into the Earth's atmosphere lump
it must cover with dust its upper part at a distance of hundreds of
kilometers not only to the West, but also to the east from the point of
impact. In actuality atmospheric optical anomalies were observed only to the
West of the Yenisey and were not observed, judging by everything, in
Yakutiya, which in no way will be coordinated with the idea about the
presence in the tunguska meteorite of gas-dust shell.

The Moments/aspects enumerated above do not exhaust all difficulties,
with which it is necessary to deal during the attempt to bring comet
hypothesis into correspondence concerning the existing/available factual
materials.
Serious difficulties appear during attempts at the interpretation from these
positions of the geomagnetic effect, caused by Tunguska explosion [ 13 ],
the estimation/evaluation of the contribution of the internal energy of the
tunguska meteorite to the total balance of explosion, mechanism of the
appearance of the subsequent (after the explosion) forest fire and number of
other moments/aspects.

Apparently, these circumstances explain the periodically undertaken
attempts at the interpretation of phenomenology of Tunguska catastrophe from
the
nontraditional positions. In the literature were discussed, in particular,
questions about antimatter nature of the tunguska meteorite [ 19, 45 ], its
equipment/accessories with the relict super-dense substance of that moved
by [43 ], about the tunguska meteorite as transient -energofore [ 13 ]. None
of these versions remained without the actual checking; however, right to
further existence they obtained, judging by everything " only two of them:
the hypothesis A.N. Dmitriev - V.K. Zhuravlev about transient nature of
the tunguska meteorite and F.Yu. Ziegel - A.N. Zolotova about his
technogenic origin. The first of them needs serious actual reinforcement,
since a question about the very possibility of existence of steady
transients remains thus far open. However, as far as the second is
concerned, at present, apparently, matured conditions for the revision of a
priori negative relation to any hypotheses, as basis of which is assumed the
assumption about the space role of reasonable life. Being in complete
agreement with V. I. Vernadskiy's study about the noosphere, the hypotheses
of this type cannot immediately be qualified as antiscientific and have a
right, at least, for the actual checking. Since final resolution of a
question about nature of Tunguska phenomenon it is not found and it is
necessary to recognize that long-standing attempts at its interpretation
within the framework of classical paradigm did not thus far bring the
decisive success, then is expedient examination and checking the alternative
versions of its explanation.